The second round was completed earlier Saturday after weather problems Thursday and Friday delayed the event. The third round will resume at 7:00 a.m. (ET) Sunday with the final round to follow.
Woody Austin and Zach Johnson are one stroke behind Pettersson at minus-10. Austin is looking at a 27-foot birdie putt at the last when he returns to the course on Sunday, while Johnson will be on the tee at the par-4 17th.
Masters champion and world No. 2 Phil Mickelson had climbed into a tie for the lead, but fell back to minus-8 through 17 holes. He shares fourth place with Adam Scott, who is through 15 holes at Muirfield Village Golf Club.
Pettersson, who is playing alongside Scott and Sean O'Hair, opened with a solid up-and-down par on one. Meanwhile, his playing partners both made lengthy birdie putts to forge a three-way tie for the lead at minus-8.
The Swede drained a 16-foot birdie putt on three to move one clear. However, he missed a 7-foot par putt on four to fall back to minus-8 and a tie for the lead with Scott.
Mickelson opened with four pars before a birdie at the fifth got him to minus-6. The two-time Masters winner then drained a 52-foot eagle putt on the par-5 seventh to join Pettersson and Scott at 8 under. Scott fell off the pace with a double bogey on five and a bogey on six.
Pettersson responded with a two-putt birdie on seven to regain the top spot. Mickelson fell two back as he bogeyed the eighth after missing the green short.
The 28-year-old Pettersson moved three clear of the field with a 5-foot birdie putt on the 10th. He parred his next two holes as he was caught atop the leaderboard.
Austin had birdied the fourth, eighth and 13th to get to 7 under. He got within one of Pettersson's lead with an eagle on 15. Austin then birdied the 17th to briefly join Pettersson in the lead. Austin's approach at the last stopped 27 feet from the hole, but play was called for the night before he could hit the putt.
Johnson was 2-over par through six holes with a birdie and three bogeys. He birdied the seventh and eighth to turn at 6 under. Johnson then reeled off four consecutive birdies from the 12th to join Austin and Pettersson in the lead at 10 under.
Pettersson, the 2005 Chrysler Championship winner, responded to the pressure with an up-and-down birdie on the 15th to move to 11 under. Shortly thereafter, play was stopped for the night.
Mickelson, after his bogey on eight, birdied the 10th to again grab a piece of the lead at 8 under. However, he found water with his third shot at the par-5 11th.
That led to a double bogey that dropped him to 6 under. Mickelson birdied 13, but tripped to another bogey on 14. The three-time major champion posted back-to-back birdies from the 15th to get back to minus-8.
Rod Pampling (66) and Trevor Immelman (69) share the clubhouse lead at 5- under-par 211. They stand alongside Brandt Jobe and Brett Wetterich, who have both completed 16 holes.
Vaughn Taylor and Robert Gamez are at minus-4 through three rounds. Tim Clark (16 holes) and O'Hair (15 holes) are also at 4 under par.
O'Hair fell off the pace after his early birdie due to bogeys on two and five. He double-bogeyed six, but got one stroke back with a birdie on seven. From there, he carded three birdies and three bogeys before play was stopped.
Jay Haas, who claimed his first major title last week at the Senior PGA Championship, stands at 1-under-par 215. He made the cut for the 590th time in his career, which tied Tim Kite for the all-time record.